昭平、惜福和哈密铁陨石的矿物岩石学研究和化学群分类

Mineralogy and Chemical Classification of Zhaoping,Xifu and Hami Iron Meteorites

详细分析了中国新近发现的3块铁陨石即:昭平、惜福和哈密的矿物组成和化学成分,并根据它们的化学元素(Ga、Ge、Ni和Ir等)含量进行了分群;昭平和惜福铁陨石分别属于ⅠAB的低Ni低Au亚群和ⅢCD铁陨石群,哈密铁陨石因为其本身的Ga和Ge的含量很低以及实验仪器的精度限制,只能得知该陨石的Ga含量小于2ppm、Ge含量小于10ppm,根据其化学元素含量.结构特征和矿物组成,初步判断哈密铁陨石应属于未分群铁陨石.

The mineralogy and bulk chemical compositions of three iron meteorites （Zhaoping, Xifu and Hami） recently found in China are reported here and the three irons are made classification on the base of their bulk chemical compositions. Zhaoping contains 93.4 mg/g Ni, 85.9μg/g Ga, 418μg/g Ge, 5.24mg/g Co, 1.94μg/g Ir, 0.774μg/g W, and 1.62μg/g Au. Zhaoping belongs to the low-Ni, low-Au subgroup of IAB. It is a coarse octahedrite and consists of kamacite, taenite, troilite, schreibersite and cohenite. Cohenite has entirely decomposed to graphite and low-Ni kamacite in our samples. Zhaoping contains some inclusions of Mn-free sarcopside which were rarely reported in IAB iron meteorites. Xifu has 74.1mg/g Ni, 58.8μg/g Ga, 150μg/gGe, and 0.913μg/g W. Xifu is a member of group ⅢCD iron meteorite. Like most of ⅢCD irons, Xifu is a coarsest octahedrite with kamacite bandwidth of 〉 3 mm, and contains kamacite, taenite and schreibersite. Carbides and graphite are not found in the sample due to the sample heterogeneous. Hami has 106 mg/g Ni, 5.36 mg/g Co and 0.922 μg/g Ir. Ga and Ge contents in Hami were not obtained because of the low concentrations and the limited precision of INAA technique. Hami is an un-grouped iron meteorite on the basis of the contents of other trace elements, structure and mineralogy. In mineralogy and structure, Hami resembles to Rafruti, another un-grouped iron meteorite.